Balance wheel for horological instruments



Ju y 23, 1968 G. F. w. GARBE BALANCE WHEEL FOR HQROLOGICAL INSTRUMENTS 2 SheetsSheet 1 Filed Sept. 21, 1966 pr EM I VE N TOR.

BY GEORGE FW GARBE 2a,,

July 23, 1968 G. F. w. GARBE 3,393,506

BALANCE WHEEL FOR HOROLOGICAL INSTRUMENTS Filed Sept. 21. 1966 2 Sheets-Sheet 2 um "I 22 I1/ 2 FIG'4 4? .lgmnnw WWII-$355 8 2 7/ W17 /.\/'\/F\IT0R I [A BY GEORGE Aw, GARBE Un wd t s Pa efi o 7 cc I 3,393,506, a I z BALANCE WHEEL FR HOROLOGICAL j INSTRUMENTS George FriedrichWilhelm Garbe, Waterhury, Coun.,' fassiguor to The United States Time Corporation, Waterbury, Conn., a corporation of Connecticut Filed Sept. 21, 1966, Ser. No. 580,975

9 Claims. (Cl. 58-107) The present invention relates to a horological instrument and more particularly to an adjustable balance bridge in a watch.

The timekeeping ability of a watch or other horological instrument is dependent upon an oscillatory 'regulating member. In a watch, the regulating member isusually a balance wheel. The balance wheel is caused; to oscillate by a mainspring or from power derivedfrom an electric battery. The balance wheel is fixed "to a staff which pivots in the'frame plates of the watch or in bridges connected to the frame plates. The balance wheel staff usually ro- 3,393,506 Patented July 23, 1968 In the drawings: 3 Y 1 I FIG. 1 is a side view of the first embodiment of the present invention; r

FIG. 2 is a top planview of the first embodiment of the present invention showing an enlarged portion of the bridge and frame plate; L

FIG. 3 is a partial side sectional view taken along; line 3--3 of FIG. 2;

FIG. 4 is a top plan view of a second embodiment of the present invention showing a portion of the bridge and frame plate; and

FIG. 5 is a partial side sectional view taken along line 5--5 of FIG. 4. I

The first embodiment of the present invention, shown in FIGS. 1-3, includes a'frame plate 1" of a. watch or other horological instrument. The frame plate 1 may ittates in jeweled bearings which provide a bearing surface I for rotation and'also restrict axial motion of the staff.

It is important that thesebearings be axially adjusted. If the balance wheel staff has too much axial play, i.e., the staff is free to move too far axially, it may cause escapement failures and position errors in the watch rate and may even injure a bearing or the staff if the watch is subjected to shocks. If the staff is held too tightly, it may not be able to swing with a sufficiently large oscillation for good timekeeping and may waste power.

For these reasons, it has been a practice .in watchmaking to provide that one of the members carrying a balance staff jewel be axially adjustable. This member is often called the balance staff bridge and its end adjustment is often referred to as an end-shake adjustment.

Some of the inexpensive balance staff bridges provide a simple nut and screw arrangement. These arrangements may cause the watchmaker or watch repairer to injure one of the jewels by turning the screw too far. In addition, the screw may be turned in the course of using the watch by vibrations and shocks, causing the loss of the correct adjustment of the bridge.

It has also been proposed to provide watch balance staff bridges with a positive adjustment. In this type of adjustment there is some mechanism to lock the bridge in position after it has ben adjusted, However, these mechanisms have been relatively expensive or difficult to manufacture.

It is the objective of the present invention to provide a balance bridge which is adjustable; which is positively locked in position after its adjustment; which is relatively inexpensive; and which is relatively simple for the watch maker or watch repairer to adjust.

In accordance with the present invention, a balance bridge is provided on which a jewel is fixedly positioned. This bridge, along with the frame plate carrying a second bearing, provides pivots for the balance wheel staff, The bridge is axially adjustable relative to the frame plate by means of a rotatable eccentric member. The eccentric member pivots so that it provides a wedging action between the frame plate and the bridge. The bridge is locked in its correct position by a screw mechanism independent of the eccentric member. The watch maker, to adjust the bridge, turns the eccentric member until the correct axial spacing is obtained. He then turns down the screw mechanism to lock the bridge in position against the eccentric member.

Other objectives will be apparent from the following detailed description of a preferred embodiment of the present invention taken in conjunction with the accompanying drawings.

self be a tongue or bridge member of the main frame plate of the-instrument, although usually it is itself one of the main frame plates of the instrument. A balance bridge 2 is positioned over the frame plate 1. The bridge 2 includes a top jewel bearing assembly'5 comprising a cylindrical bearing jewel 5a for journaling and a cap jewel (end stone) 5!) for thrust. It is understood, however, that the bearings for the staff may be of other constructions. A balance wheel 3 is fixed on its staff 4 and is oscillated by a flat spiral return spring 4a. The balance wheel is impulsed from a mainspring (not shown) or is itself part of an electrical motive system including a battery (not shown). The oscillation of the balance wheel 3 provides timekeeping regulation. The staff 4 is positioned between top bearing jewel assembly 5 and a similar bottom jewel assembly 9 within the frame plate 1.

A shoulder 10 of the bridge 2 is sued as a support member for one end of the bridge. The other end of the bridge is fixed, in conventional manner, with the adjustable end held in a cantilevered fashion. As an alternative, the other end may be free and the adjustable end may hold the bridge in a cantilevered manner. The bridge is free to move axially due to its inherent flexibility and the manner it is held at its other end by means of the adjustment mechanism of the present invention. The shoulder 10 rests against the head 11 of the eccentric member 12. The eccentric member 12 has a top shank portion 30 having a slotted portion 13, so that it may be rotated, and a bottom shank portion 14. The bottom shank portion 14 fits and pivots within round hole 15 of frame plate 1. The head 11, as is shown by the dotted lines in FIG. 2, is eccentrically fixed to the shank portions 30 and 14. When eccentric member 12 is rotated, more of its head portion 11 is brought either toward the balance staff or away from the balance staff. When the head 11 is rotated to its extreme position toward the staff (shown by dotted lines of FIG. 2) it acts against shoulder 10, in a wedge-like manner, and axially raises the bridge 2 as far as it can be raised.

A tightening screw 16 is positioned within a cavity portion 21 of balance bridge 2. Screw 16 has a head portion 22, a slot 17 for turning, a shank having an upper portion 18 having a smooth exterior face and a lower portion 19 having exterior screw threads. The screw threads of lower portion 19 screw into the threads of hole 20 of frame plate 1. The screw 16 may, alternatively, have other forms. For example, a Phillips head may be used in place of slots 17. As another example, the shank may be threaded with exterior screw threads for its entire length, i.e., both upper portion 18 and lower portion 19.

After the eccentric member 12 has been turned so that the bridge 2 is axially adjusted, the watch maker tightens down screw 16 to retain the assembly in positive locked position.

The embodiment shown in FIGS. 4 and is similar in many respects to the embodiment of prior FIGS. 1-3, and similar parts are numbered the same.

In the embodiment of FIGS. 4 and 5 the eccentric member 42 consists of a head portion 41 having a slot I 43 for its turning. The head is eccentrically fixed on the shank portion 44 of the eccentric member 42. The shank portion fits and pivots within a hole 45 in the frame plate 1. A beveled shoulder 46 on the head 41 acts against shoulder 50 of bridge 2 to support and axially space the bridge.

Modifications may be made in the present invention within the scope of the subjoined claims. For example, the eccentric member may be constructed with a top shank portion 30, as in FIGS. 1-3, :and without the bottom shank portion 14 which fits in hole 15. As another example, instead of one end of the bridge being fixed and the other adjustable, both ends may be adjustable utilizing the adjusting mechanism of the present invention.

I claim: 1. A horological instruments having a regulating member mounted on a staff, a frame member carrying a first pivot for the staff, and a bridge carrying a second pivot for said staff;

means to axially adjust an end of said bridge relative to said frame plate,

said adjustment means including an eccentric member having an eccentric head positioned between said bridge and said frame member; said eccentric member being rotatable to axially position said bridge, means to pivot said eccentric member, and

a locking screw adjustably connecting said bridge and said frame member.

2. A horological instrument as in claim 1 wherein the means to pivot said eccentric member includes a shank portion fixed to said eccentric head and a hole in said frame member within which said shank portion rotatably pivots.

3. A horological instrument as in claim 2 wherein the eccentric head is slotted so that the eccentric member may be rotated.

4. A horological instrument as in claim 1 wherein the means to pivot said eccentric member includes a. shank portion fixed to said eccentric head and a hole in said bridge within which said shank portion rotatably pivots.

5. A horological instrument as in claim 4 wherein the shank portion has a top slot whereby the eccentric member may be rotated.

6. A horological instrument as in claim 1 wherein the locking screw consists of a screw having a slotted head, a shank integral with said head and having a top smooth exterior portion and a screw threaded bottom portion.

7. A horological instrument as in claim 6 wherein said screw head fits within a cavity in the bridge, said top portion of the shank rotates in a hole in said bridge, and said lower portion is threaded into threads in a hole in said frame member.

8. A horological instrument as in claim 1 wherein said regulating member is a balance wheel and the instrument is a watch.

9. A horological instrument as in claim 1 wherein the locking screw consists of a screw having a shank and a head, said shank being threaded for substantially its en tire length.

References Cited FOREIGN PATENTS 5/ 1963 Switzerland. 

1. A HOROLOGICAL INSTRUMENT HAVING A REGULATING MEMBER MOUNTED ON A STAFF, A FRAME MEMBER CARRYING A FIRST PIVOT FOR THE STAFF, AND A BRIDGE CARRYING A SECOND PIVOT FOR SAID STAFF; MEANS TO AXIALLY ADJUST AN END OF SAID BRIDGE RELATIVE TO SAID FRAME PLATE, SAID ADJUSTMENT MEANS INCLUDING AN ECCENTRIC MEMBER HAVING AN ECCENTRIC HEAD POSITIONED BETWEEN SAID BRIDGE AND SAID FRAME MEMBER; SAID ECCENTRIC MEMBER BEING ROTATABLE TO AXIALLY POSITION SAID BRIDGE, MEANS TO PIVOT SAID ECCENTRIC MEMBER, AND A LOCKING SCREW ADJUSTABLY CONNECTING SAID BRIDGE AND SAID FRAME MEMBER. 